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L.Suresh
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 Posted: Wed Jan 19, 2005 9:21 pm Post subject: Names in Class Scope |
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typedef int c;
enum { i = 1 };
class X {
char v[i]; // error: i refers to ::i, but when reevaluated is X::i
int f() { return sizeof(c); } // OK: X::c
char c;
enum { i = 2 };
};
This is the example in 3.3.6/5
How come the "c" in the function int f() {...}
interpreted as X::c and not an error when the name
introduced by the typedef is also in scope.
Thanks for your time.
--lsu
[ See http://www.gotw.ca/resources/clcm.htm for info about ]
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Seungbeom Kim
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| Posted: Sun Jan 23, 2005 2:42 am Post subject: Re: Names in Class Scope |
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L.Suresh wrote:
| Quote: | typedef int c;
enum { i = 1 };
class X {
char v[i]; // error: i refers to ::i, but when reevaluated is X::i
int f() { return sizeof(c); } // OK: X::c
char c;
enum { i = 2 };
};
This is the example in 3.3.6/5
How come the "c" in the function int f() {...}
interpreted as X::c and not an error when the name
introduced by the typedef is also in scope.
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A name in an enclosed scope hides the same name in an enclosing scope.
Unless you use the :: operator, of course.
--
Seungbeom Kim
[ See http://www.gotw.ca/resources/clcm.htm for info about ]
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L.Suresh
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| Posted: Sun Jan 23, 2005 10:19 am Post subject: Re: Names in Class Scope |
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Then how come char v[i] is an error? Why doesnt the enum { i = 2} hide
the one in the enclosing scope?
It's because, according to 3.3.6/2
"A name N used in a class S shall refer to the same declaration in its
context and when re-evaluated in the completed scope of S. "
In sizeof(c), does not "c" refer to the typedef, and when reevaluated
refers to the char?
--lsu
[ See http://www.gotw.ca/resources/clcm.htm for info about ]
[ comp.lang.c++.moderated. First time posters: Do this! ]
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kanze@gabi-soft.fr
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| Posted: Mon Jan 24, 2005 10:40 pm Post subject: Re: Names in Class Scope |
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L.Suresh wrote:
| Quote: | Then how come char v[i] is an error? Why doesnt the enum { i =
2} hide the one in the enclosing scope?
It's because, according to 3.3.6/2
"A name N used in a class S shall refer to the same
declaration in its context and when re-evaluated in the
completed scope of S. "
In sizeof(c), does not "c" refer to the typedef, and when
reevaluated refers to the char?
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Because of §3.3.6/1, point 1: "The potential scope of a name
declared in a class consists not only of the declarative region
following the name's declarator, but also of all function
bodies, default arguments, and constructor ctor-initializers in
that class (including such things as nested classes)." If you
modify your example to read:
typedef int c;
enum { i = 1 };
class X {
char v[sizeof(c)]; // error: c refers to ::ic but when
reevaluated is X::c
int f() { return i; } // OK: X::i
char c;
enum { i = 2 };
};
Within the function, it is as if the function definition
followed the complete class definition. Outside of the
function, the rule you cite applies.
--
James Kanze GABI Software http://www.gabi-soft.fr
Conseils en informatique orientée objet/
Beratung in objektorientierter Datenverarbeitung
9 place Sémard, 78210 St.-Cyr-l'École, France, +33 (0)1 30 23 00 34
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